From the California Department of Insurance website:
Health insurance coverage is marketed to consumers through individual policies or group policies. Individual health insurance coverage should be pursued when your employer does not offer health insurance as a benefit of employment, when you cannot be named as the dependent on another person’s insurance policy, or when you are not a member of a professional or trade association that offers group coverage. Many consumers are self-employed, contract employees, or work for small employers and do not have access to a group policy secured by an employer. Individual coverage can be obtained by contacting a licensed health insurance agent or broker. You will need to complete an application that includes your medical history, which will be reviewed by a medical underwriter at the health insurance company. If you meet the underwriting qualifications and are issued a policy, the company may not cover preexisting conditions up to one year after the effective date of the policy. However, if you have been previously insured under an individual or group policy without a break in coverage of more than 62 days, your new insurance company must apply the prior creditable coverage (refer to the "Health Insurance Terms" on page 15) towards any waiting period for preexisting conditions.
Individual health insurance companies may reject your application based on your medical history.
http://www.insurance.ca.gov/0100-con...e.cfm#marketed